Method of manufacturing semiconductor integrated circuit device

ABSTRACT

Using an STI insulating film in a high breakdown voltage MOSFET leads to deterioration in reliability due to impact ionization near the bottom corner of a drain isolation insulating film. 
     The invention provides a method of manufacturing a semiconductor integrated circuit device including forming a hard mask film, an opening therein, and a sidewall insulating film on the side surface thereof; forming a shallow trench in the opening with the hard mask film as a mask and oxidizing at least an exposed portion; filling the trench with an insulating film and then removing it so as to leave it outside the trench in the opening and thereby forming a drain offset STI insulating film inside and outside the trench; and forming a gate electrode extending from the upper portion of a gate insulating film in an active region contiguous thereto to the upper portion of the drain offset insulating film.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2014-135896 filed onJul. 1, 2014 including the specification, drawings, and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a method of manufacturing asemiconductor integrated circuit device (or semiconductor device), forexample, a method applicable to a semiconductor integrated circuitdevice having a high breakdown voltage transistor.

Japanese Unexamined Patent Application Publication No. 2011-187530(Patent Document 1) or U.S. Patent Publication No. 2011-215423 (PatentDocument 2) corresponding thereto relates to a CMOS (complementarymetal-oxide-semiconductor) semiconductor integrated circuit. Disclosedherein is a technology of forming a trench in the surface of asemiconductor substrate and thereby providing an insulated gate FET(field effect transistor) having a high drain current. This documentdiscloses, for example, a MOSFET having a trench extending beneath agate from a source contact region to a drain contact region.

Japanese Unexamined Patent Application Publication No. 2012-18973(Patent Document 3) or U.S. Patent Publication No. 2012-7151 (PatentDocument 4) corresponding thereto relates to a CMOS semiconductorintegrated circuit having integrated high breakdown voltage transistors.Disclosed herein is a high breakdown voltage MIS(metal-insulator-semiconductor) FET having a trench or the like runningparallel to or perpendicular to a channel direction in a channel regionor the like.

Japanese Unexamined Patent Application Publication No. 2011-66067(Patent Document 5) or U.S. Patent No. 2012-8692352 (Patent Document 6)corresponding thereto relates to a CMOS semiconductor integrated circuithaving high breakdown voltage lateral transistors integrated therein.Disclosed herein is a CMOS semiconductor integrated circuit in whichhigh breakdown voltage lateral MOSFETs are isolated from each other by aDTI (deep trench isolation) or the like.

PATENT DOCUMENTS

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2011-187530

[Patent Document 2] U.S. Patent Publication No. 2011-215423

[Patent Document 3] Japanese Unexamined Patent Application PublicationNo. 2012-18973

[Patent Document 4] U.S. Patent Publication No. 2012-7151

[Patent Document 5] Japanese Unexamined Patent Application PublicationNo. 2011-66067

[Patent Document 6] U.S. Pat. No. 8,692,352

SUMMARY

In the manufacture of a high breakdown voltage MOSFET (for example,LDMOSFET) or the like, using a LOCOS type field insulating film or thelike for element isolation or another isolation prolongs a treatmentstep and thereby raises a manufacture cost. The present inventors haveon the other hand revealed that when an STI type field insulating filmor the like is used, high-energy electrons are generated in the vicinityof the bottom corner portion of a drain isolation insulating film due toimpact ionization and the resulting high breakdown voltage MOSFET or thelike has deteriorated reliability. Such a tendency is particularlymarked in a high breakdown voltage P type LDMOSFET.

A means of overcoming such a problem will next be described. Anotherproblem and novel features will be apparent from the description hereinand accompanying drawings.

Of the embodiments disclosed herein, typical ones will next be outlinedbriefly.

First embodiment of the present application is outlined below. There isprovided a method of manufacturing a semiconductor integrated circuitdevice including the following steps: (1) first, forming a hard maskfilm on a first main surface of a semiconductor wafer and making a firstopening in the hard mask film in a first region on the first mainsurface; (2) then, forming a sidewall insulating film on the sidesurface of the hard mask film of the first opening; (3) then, with thehard mask film and the sidewall insulating film as masks, forming afirst shallow trench in a semiconductor region surface of the first mainsurface in the first opening; (4) then, oxidizing at least an exposedportion of the inner surface of the first shallow trench and thesemiconductor region surface of the first main surface in the firstopening; (5) then, filling the first shallow trench and the firstopening with an insulating film; (6) then, removing the insulating filmoutside the first shallow trench so as to leave the insulating filmoutside the first shallow trench in the first opening and therebyforming a drain offset STI insulating film both inside and outside thefirst shallow trench; and (7) then, forming a first gate electrode thatextends from an upper portion of the gate insulating film in a firstactive region adjacent to the drain offset STI insulating film to anupper portion of the drain offset insulating film.

Advantages available by typical embodiments, among those disclosedherein, will next be described simply.

According to First Embodiment of the present application, a highbreakdown voltage MOSFET having improved reliability can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) for describing a method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 2 is a device cross-sectional view of a low breakdown voltagedevice region during the wafer process (a hard mask primary processingstep) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 3 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of forming a sidewallsilicon oxide film-based insulating film for processing) for describingthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 4 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of forming a sidewallinsulating film for processing) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application;

FIG. 5 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (an offset drain shallow trenchetching step) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 6 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of removing the sidewallinsulating film for processing) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application;

FIG. 7 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of etching a shallowtrench of an element isolation portion or the like) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 8 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a step of etching a shallowtrench of an element isolation portion or the like) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 9 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (an inner wall oxide filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 10 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (an inner wall oxide filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 11 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a buried insulating filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 12 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a buried insulating filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 13 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a CMP step) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 14 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a CMP step) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 15 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a buried insulating filmetch-back step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 16 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a buried insulating filmetch-back step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 17 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a hard mask removal step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application;

FIG. 18 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a hard mask removal step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application;

FIG. 19 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a gate polysilicon filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 20 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a gate polysilicon filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 21 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a gate electrode processingstep) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 22 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a gate electrode processingstep) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 23 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a step of introducing an LDDregion or the like) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 24 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a gate sidewall formation step)for describing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application;

FIG. 25 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a gate sidewall formation step)for describing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application;

FIG. 26 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a P type high-concentrationsource-drain region introduction step) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application;

FIG. 27 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (an N type and P typehigh-concentration source-drain regions introduction step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application;

FIG. 28 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a salicide step) for describingthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 29 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a salicide step) for describingthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 30 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a premetal insulating layerformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 31 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a premetal insulating layerformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 32 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (an additional isotropic etchingstep) following the step of FIG. 5 for describing a modification example(Modification Example 1), in hard mask, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 33 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) corresponding to the step of FIG. 1 for describing a modificationexample (Modification Example 2), in hard mask, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application;

FIG. 34 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of forming a sidewallsilicon oxide-based insulating film for processing) corresponding to thestep of FIG. 3 for describing the modification example (ModificationExample 2), in hard mask, of the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 35 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of forming a sidewallinsulating film for processing) corresponding to the step of FIG. 4 fordescribing the modification example (Modification Example 2), in hardmask, of the method of manufacturing a semiconductor integrated circuitdevice according to First Embodiment of the present application;

FIG. 36 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (an offset drain shallow trenchisotropic etching step) corresponding to the step of FIG. 5 fordescribing the modification example (Modification Example 2), in hardmask, of the method of manufacturing a semiconductor integrated circuitdevice according to First Embodiment of the present application;

FIG. 37 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) corresponding to the step of FIG. 1 for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 38 is a device cross-sectional view of a high breakdown voltagedevice region during the wafer process (a hard mask removal step)corresponding to the step of FIG. 17 for describing the modificationexample (Modification Example 3), in hard mask, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application;

FIG. 39 is a device cross-sectional view of a low breakdown voltagedevice region during the wafer process (a hard mask removal step)corresponding to the step of FIG. 18 (FIG. 38) for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 40 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (an underlying insulating filmremoval step) for describing the modification example (ModificationExample 3), in hard mask, of the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 41 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (an underlying insulating filmremoval step) corresponding to the step of FIG. 40 for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 42 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a gate polysilicon filmformation step) corresponding to the step of FIG. 19 for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 43 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a gate polysilicon filmformation step) corresponding to the step of FIG. 20 (FIG. 42) fordescribing the modification example (Modification Example 3), in hardmask, of the method of manufacturing a semiconductor integrated circuitdevice according to First Embodiment of the present application;

FIG. 44 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a step of removing the sidewallinsulating film for processing) corresponding to the step of FIG. 6 fordescribing a modification example (Modification Example 4), in cornerrounding of a trench to be filled with an offset drain isolationinsulating film, of the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication;

FIG. 45 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask secondary processingstep) corresponding to the step of FIG. 7 (first half part) fordescribing the modification example (Modification Example 5), in aformation process of a trench to be filled with an offset drainisolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 46 is a device cross-sectional view of a low breakdown voltagedevice region during the wafer process (a hard mask secondary processingstep) corresponding to the step of FIG. 45 for describing themodification example (Modification Example 5), in a formation process ofa trench to be filled with an offset drain isolation insulating film, ofthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 47 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a shallow trench simultaneousetching step) corresponding to the step of FIG. 7 (latter half part) fordescribing the modification example (Modification Example 5), in aformation process of a trench to be filled with an offset drainisolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application;

FIG. 48 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a shallow trench simultaneousetching step) corresponding to the step of FIG. 47 for describing themodification example (Modification Example 5), in a formation process ofa trench to be filled with an offset drain isolation insulating film, ofthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 49 is a process block flow chart for describing the outline of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application;

FIG. 50 is a whole chip top view showing one example of a chip layout inFirst Embodiment (including modification examples) of the presentapplication;

FIG. 51 is a schematic cross-sectional view (DTI isolation structure) ofa device corresponding to the A-B cross-section of FIG. 50 showing oneexample of an element isolation structure and the like in FirstEmbodiment (including modification examples) of the present application;

FIG. 52 is an enlarged chip top view of an upper-surface cutout portionR1 of the high breakdown voltage region shown in FIG. 50;

FIG. 53 is an enlarged chip top view of an upper-surface cutout portionR2 of the low breakdown voltage region shown in FIG. 50; and

FIG. 54 is a schematic cross-sectional view (DTI & SOI isolationstructures) of a device corresponding to the A-B cross-section of FIG.50 showing another example of the element isolation structure and thelike in First Embodiment (including modification examples) of thepresent application.

DETAILED DESCRIPTION

[Outline of Embodiment]

First, typical embodiments disclosed herein will be outlined.

1. A method of manufacturing a semiconductor integrated circuit deviceincluding the following steps: (a) forming a hard mask film on a firstmain surface of a semiconductor wafer and making a first opening in thehard mask film in a first region on the first main surface; (b) formingsidewall insulating films on the side surfaces of the hard mask film ofthe first opening, respectively; (c) forming a first shallow trench in asemiconductor region surface of the first main surface in the firstopening, with the hard mask film and the sidewall insulating films asmasks; (d) after the step (c), oxidizing at least an exposed portion ofan inner surface of the first shallow trench and the semiconductorregion surface of the first main surface in the first opening; (e) afterthe step (d), filling the first shallow trench and the first openingwith an insulating film; (f) after the step (e), removing the insulatingfilm outside the first shallow trench so as to leave the insulating filmoutside the first shallow trench in the first opening and therebyforming a drain offset STI insulating film inside and outside the firstshallow trench; and (g) after the step (f), forming a first gateelectrode from an upper portion of a gate insulating film in a firstactive region contiguous to the drain offset STI insulating film to anupper portion of the drain offset insulating film.

2. The method of manufacturing a semiconductor integrated circuit deviceas described above in 1, further including the following steps: (h)after the step (c) but before the step (d), making a second opening inthe hard mask film in a second region on the first main surface andthereby forming a second shallow trench in a semiconductor regionsurface of the first main surface in the second opening. In the step(d), at least an exposed portion of the inner surface of the secondshallow trench is oxidized. In the step (e), the second shallow trenchand the second opening are filled with an insulating film. In the step(f), the insulating film outside the second shallow trench is removed toform an interelement STI insulating film in the second shallow trench.In the step (g), a second gate electrode is formed on the gateinsulating film in a second active region contiguous to the secondshallow trench.

3. In the method of manufacturing a semiconductor integrated circuitdevice as described above in 1 or 2, the hard mask film has a siliconnitride-based insulating film as a main component film thereof.

4. The method of manufacturing a semiconductor integrated circuit deviceas described above in 3, further including the following step: (i) afterthe step (f) but before the step (g), removing the silicon nitride-basedinsulating film.

5. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 1 to 4, the hard mask film has apolysilicon film as an upper half main portion thereof.

6. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 1 to 5, the width of the firstshallow trench at the time when the step (d) is started is greater thanthe width between the sidewall insulating films at the time when thestep (c) is completed.

7. The method of manufacturing a semiconductor integrated circuit deviceas described above in any one of 1 to 6, further including the followingstep: (j) after the step (c) but before the step (d), removing thesidewall insulating films.

8. A method of manufacturing a semiconductor integrated circuit deviceincluding the following steps: (a) forming a hard mask film on a firstmain surface of a semiconductor wafer and making a first opening in thehard mask film in a first region on the first main surface; (b) formingsidewall insulating films on the side surfaces of the hard mask film ofthe first opening, respectively; (c) forming a first shallow trench in asemiconductor region surface of the first main surface in the firstopening, with the hard mask film and the sidewall insulating films asmasks; (d) after the step (c), making a second opening in the hard maskfilm in a second region on the first main surface and forming a secondshallow trench in a semiconductor region surface of the first mainsurface in the second opening; (e) after the step (d), oxidizing atleast an exposed portion of an inner surface of the first shallowtrench, an inner surface of the second shallow trench, and thesemiconductor region surface of the first main surface in the firstopening; (f) after the step (e), filling the first shallow trench, thesecond shallow trench, the first opening, and the second opening with aninsulating film; (g) after the step (f), removing the insulating filmoutside the first shallow trench and the second shallow trench so as toleave the insulating film outside the first shallow trench in the firstopening and thereby forming a drain offset STI insulating film insideand outside the first shallow trench and forming an interelement STIinsulating film in the second shallow trench; and (h) after the step(g), forming a first gate electrode from an upper portion of a gateinsulating film in a first active region contiguous to the drain offsetSTI insulating film to an upper portion of the drain offset insulatingfilm and forming a second gate electrode on a gate insulating film in asecond active region contiguous to the second shallow trench.

9. In the method of manufacturing a semiconductor integrated circuitdevice as described above in 8, the hard mask film has a siliconnitride-based insulating film as a main component film thereof.

10. The method of manufacturing a semiconductor integrated circuitdevice as described above in 9, further including the following step:(i) after the step (g) but before the step (h), removing the siliconnitride-based insulating film.

11. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 8 to 10, the hard mask film hasa polysilicon film as an upper half main portion thereof.

12. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 8 to 11, the width of the firstshallow trench at the time when the step (e) is started is greater thanthe width between the sidewall insulating films at the time when thestep (c) is completed.

13. The method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 8 to 12, further including thefollowing step: (j) after the step (c) but before the step (e), removingthe sidewall insulating films.

14. A method of manufacturing a semiconductor integrated circuit deviceincluding the following steps: (a) forming a hard mask film on a firstmain surface of a semiconductor wafer and making a first opening in thehard mask film in a first region on the first main surface; (b) formingsidewall insulating films on the side surfaces of the hard mask film ofthe first opening, respectively; (c) after the step (b), forming asecond opening in the hard mask film in a second region on the firstmain surface; (d) forming a first shallow trench in a semiconductorregion surface of the first main surface in the first opening andforming a second shallow trench in a semiconductor region surface of thefirst main surface in the second opening, with the hard mask film andthe sidewall insulating films as masks; (e) after the step (d),oxidizing an exposed portion of an inner surface of the first shallowtrench, an inner surface of the second shallow trench, and thesemiconductor region surface of the first main surface in the firstopening; (f) after the step (e), filling the first shallow trench, thesecond shallow trench, the first opening, and the second opening with aninsulating film; (g) after the step (f), removing the insulating filmoutside the first shallow trench and the second shallow trench so as toleave the insulating film outside the first shallow trench in the firstopening and thereby forming a drain offset STI insulating film insideand outside the first shallow trench and an interelement STI insulatingfilm in the second shallow trench; and (h) after the step (g), forming afirst gate electrode from an upper portion of a gate insulating film ina first active region contiguous to the drain offset STI insulating filmto an upper portion of the drain offset insulating film and a secondgate electrode on a gate insulating film in a second active regioncontiguous to the second shallow trench.

15. In the method of manufacturing a semiconductor integrated circuitdevice as described above in 14, the hard mask film has a siliconnitride-based insulating film as a main component film thereof.

16. The method of manufacturing a semiconductor integrated circuitdevice as described above in 15, further including the following step:(i) after the step (g) but before the step (h), removing the siliconnitride-based insulating film.

17. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 14 to 16, the hard mask film hasa polysilicon film as an upper half main portion thereof.

18. In the method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 14 to 17, the width of the firstshallow trench at the time when the step (e) is started is greater thanthe width between the sidewall insulating films at the time when thestep (d) is completed.

19. The method of manufacturing a semiconductor integrated circuitdevice as described above in any one of 14 to 18, further including thefollowing step: (j) after the step (d) but before the step (e), removingthe sidewall insulating films.

[Explanation of Description Manner, Basic Terms, and Usage in thePresent Application]

1. In the present application, a description of an embodiment may bemade after divided in a plurality of sections if necessary for the sakeof convenience. These sections are not independent from each otherunless otherwise particularly specified, but they may each be a part ofa single example or one of them may be a partial detail of the other ora modification example of a part or whole of the other one. Inprinciple, a description of a portion similar to that described beforeis omitted. Moreover, constituent components in each embodiment are notessential unless otherwise particularly specified, limited to the numbertheoretically, or apparent from the context.

The term “semiconductor device” or “semiconductor integrated circuitdevice” as used herein refers mainly to various transistors (activeelements) alone, devices obtained by integrating such a transistor as amain component, a resistor, a capacitor, and other components on asemiconductor chip (for example, a single crystal silicon substrate) orthe like, and devices obtained by packaging a semiconductor chip and thelike. Representative examples of the various transistors include MISFETs(metal insulator semiconductor field effect transistors) typified byMOSFETs (metal oxide semiconductor field effect transistors).Representative examples of the integrated circuit constitution in thiscase include CMIS (complementary metal insulator semiconductor)integrated circuits typified by CMOS (complementary metal oxidesemiconductor) integrated circuits having an N channel type MISFET and aP channel type MISFET in combination.

A wafer process of today's semiconductor integrated circuit devices,that is, LSI (large scale integration) is usually classified into twoparts: an FEOL (front end of line) process and a BEOL (back end of line)process. The FEOL process roughly ranges from a step of carrying in asilicon wafer as a raw material to a premetal step (a step includingformation of an interlayer insulating film and the like between thelower end of an M1 wiring layer and a gate electrode structure,formation of a contact hole, embedding of a tungsten plug, and thelike). The BEOL process roughly ranges from formation of the M1 wiringlayer to formation of a pad opening in a final passivation film on analuminum-based pad electrode (in a wafer level package process, thisprocess is also included).

In the present application, when a wiring and a via belonging to thesame interlayer insulating film will be referred to, attention is paidto the layer of the interlayer insulating film and they are called bythe name of the same layer. This means that a via between a first-layerburied wiring and a second-layer buried wiring is referred to as“second-layer via”.

2. Similarly, even when such a term “X comprised of A” or the like isused in association with a material, a composition, or the like in thedescription of the embodiment or the like, it does not exclude amaterial, composition, or the like containing a component other than Aas one of the main constituent components thereof unless otherwiseparticularly specified or apparent from the context that it excludessuch a material, composition, or the like. For example, with regard to acomponent, the term means “X containing A as a main component” or thelike. It is needless to say that even the term “silicon member” is notlimited to a pure silicon member but embraces a multi-element alloy suchas SiGe alloy containing silicon as a main component or a membercontaining, in addition, another additive and the like.

Similarly, it is needless to say that the term “silicon oxide film”,“silicon oxide-based insulating film”, or the like means not only arelatively pure undoped silicon oxide (undoped silicon dioxide)insulating film but also another insulating film having silicon oxide asa main component thereof. For example, a silicon oxide-based insulatingfilm doped with an impurity such as TEOS-based silicon oxide, PSG(phosphorus silicate glass), or BPSG (borophosphosilicate glass)insulating film is also a silicon oxide film. Additional examples of thesilicon oxide film or silicon oxide-based insulating film include athermal oxide film, a CVD oxide film, and a film obtained by the methodof application such as SOG (spin on glass) and nano-clustering silica(NSC) films. Further, low-k insulating films such as FSG (fluorosilicateglass), SiOC (silicon oxycarbide), carbon-doped silicon oxide, and OSG(organosilicate glass) films are also silicon oxide films or siliconoxide-based insulating films. Still further, silica-based low-kinsulating films (porous insulating films, in which the term “porous”embraces molecularly porous) obtained by introducing voids into a membersimilar to those mentioned above are silicon oxide films or siliconoxide-based insulating films.

Not only the silicon oxide-based insulating films but also siliconnitride-based insulating films are silicon-based insulating filmsordinarily used in semiconductor fields. Examples of materials belongingto silicon nitride-based insulating films include SiN, SiCN, SiNH, andSiCNH. The term “silicon nitride” as used herein means both SiN and SiNHunless otherwise specifically indicated that it is not. Similarly, theterm “SiCN” means both SiCN and SiCNH unless otherwise specificallyindicated that it does not.

Although SiC has a property similar to that of SiN, SiON (SiOC, SiOCN)needs to be classified as a silicon oxide-based insulating film in manycases. When SiON is used as an etch stop film or a reference lightreflection accelerating film, it has a property similar to SiC, SiN, orthe like. These oxides and nitrides (carbides, carbonitrides) aretherefore classified, depending on which is the main component of them.

Silicon nitride-based insulating films such as silicon nitride films arefrequently used as an etch stop film in SAC (self-aligned contact)technology, that is, a CESL (contact etch-stop layer). They are alsoused as a stress imparting film in SMT (stress memorization technique).

Similarly, the term “nickel silicide” usually means nickel monosilicidebut it embraces not only relatively pure one but also alloy, mixedcrystal, or the like having nickel monosilicide as a main constitutingcomponent. The silicide may be not only nickel silicide but also cobaltsilicide, titanium silicide, tungsten silicide or the like which hasconventionally been used successfully. As a metal film for silicidation,as well as a Ni (nickel) film, for example, a Ni—Pt alloy film (an alloyfilm between Ni and Pt), a Ni—V alloy film (alloy film between Ni andV), an Ni—Pd alloy film (alloy film between Ni and Pd), an Ni—Yb alloyfilm (alloy film between Ni and Yb), or an Ni—Er alloy film (alloy filmbetween Ni and Er) can be used. Such a silicide having nickel as a mainmetal element thereof will hereinafter be called “nickel-basedsilicide”, collectively.

3. The term “wafer” typically means a single-crystal silicon wafer onwhich a semiconductor integrated circuit device (which will equallyapply to a semiconductor device or an electronic device) is formed. Itis needless to say that it also embraces a composite wafer of aninsulating substrate and a semiconductor layer or the like, such as anepitaxial wafer, an SOT substrate, or an LCD glass substrate.

4. Preferred examples of the shape, position, attribute, and the likewill be shown below, however, it is needless to say that the shape,position, attribute, and the like are not strictly limited to thesepreferred examples unless otherwise specifically indicated or apparentfrom the context that they are strictly limited to these preferredexamples. Therefore, for example, the term “square” embraces“substantially square”; the term “orthogonal” embraces “substantiallyorthogonal”, and the term “coincide with” embraces “substantiallycoincide with”. This also applies to the terms “parallel” and “rightangle”. For example, a position away by about 10 degrees from a completeparallel position belongs to the term “parallel”.

The term “whole region”, “overall region”, “entire region”, or the likeembraces “substantially whole region”, “substantially overall region”,“substantially entire region” or the like. For example, the term “wholeregion”, “overall region”, or “entire region” embraces a portion of theregion accounting for 80% or more of the area thereof. This also appliesto “whole circumference”, “whole length”, or the like.

Further, with regard to the shape of a member or the like, the term“rectangular” embraces “substantially rectangular”. For example, when amember has a rectangular portion and an unrectangular portion and anarea of the latter portion is less than about 20% of the whole area,this member can be regarded rectangular. This also applies to the term“circular” or the like. In this case, when a circular body is divided, aportion having this divided component portion inserted or exerted is apart of the circular body.

With regard to the term “periodic”, the term “periodic” embraces“substantially periodic”. When a difference in periodicity of individualcomponents is less than about 20%, these components are regarded“periodic”. Further, when less than about 20% of the components to beanalyzed are outside the above range, these components can be regarded“periodic” as a whole.

The definition in this section is a general one. When a differentdefinition is applied to the following individual descriptions, priorityis given to the definition used in the individual descriptions. Withregard to a portion not specified in the individual descriptions, thedefinition or specification in this section is effective unlessotherwise definitely denied.

5. When reference is made to any specific numeric value or amount, thespecific numeric value or amount may be exceeded or may be underrununless otherwise particularly specified, limited to the numbertheoretically, or apparent from the context that it is not exceeded orunderrun.

6. The term “LDMOSFET” (lateral double-diffused MOSFET), a mainobjective in the present application, has historically meant a lateralMOSFET having a gate length determined by double diffusion, but now itwidely embraces a lateral MOSFET having, on the surface side thereof, asource, a drain, and a gate irrespective of double diffusion. Needlessto say, it embraces a MOSFET having, on the surface side thereof, asource, a drain, and a gate and having, on the back side surfacethereof, one of such electrodes formed using a sinker, a buried plug, orthe like. In the present application, the term “LDMOSFET” is used in thelatter meaning (in a broad sense). The term LDMOSFET, that is, anobjective of the present application, widely embraces such a lateralMOSFET whether it is a single transistor or an integrated circuit. Inthe present application, as one example of the LDMOSFET, mainly a Pchannel type LDMOSFET will be described specifically, but thisdescription can also be applied to an N channel type LDMOSFET.

In addition, it is needless to say that as a high breakdown voltagetransistor (“high breakdown voltage transistor and the like” includes ahigh breakdown voltage transistor and a power device), various lateralMOSFETS can be used and further, vertical MOSFETS can be used incombination. In addition, as the high breakdown voltage transistor andthe like, IGBT (insulated gate bipolar transistor) and the like can alsobe used in combination.

The term “STI (shallow trench isolation) structure”, “STI insulatingfilm”, “STI process”, or the like as used herein does not mean only astandard STI process, that is, a non-self-aligned STI (N-STI:normal-STI) process, self-aligned STI process (SA-STI, self-aligned STI)process, or the like. It widely embraces an element isolation process orthe like which is different from a LOCOS (local oxidation or silicon)process or DTI (deep trench isolation) and is an element isolationtechnology or the like using filling of a trench with an insulating filmand planarization of the film in combination. A modified STI processsuch as formation process of a drain offset STI insulating film 25(refer to FIG. 15) is therefore included in the STI process describedherein.

The term “SA-STI” as used herein widely means not only a process for aflash memory or the like but also an STI process in which polysilicon islaid on the lower layer portion of a hard mask.

[Details of Embodiment]

The embodiments will next be described more specifically. In all thedrawings, the same or like members will be identified by the same orlike symbols or reference numerals and overlapping descriptions will beomitted in principle.

In the accompanying drawings, hatching or the like is sometimes omittedeven from the cross-section when it makes the drawing complicated orwhen a member can be distinguished clearly from a vacant space. Inrelation thereto, even a planarly closed hole may be shown without abackground contour thereof when it is obvious from the description orthe like. On the other hand, hatching may be added even to a drawingwhich is not a cross section, in order to clearly show that it is not avacant space.

With regard to alternative naming, when one of two members or the likeis called “first” and the other is called “second”, they are sometimesnamed according to the typical embodiment. It is needless to say,however, even when one of two members is called “first member”, theirnaming is not limited to this choice.

1. Description on a Main Process of a Basic Example of a Method ofManufacturing a Semiconductor Integrated Circuit Device According toFirst Embodiment of the Present Application (Mainly, FIGS. 1 to 31)

In the following example, a process using an epitaxial Si wafer (whichwill hereinafter be called “P type Si epitaxial wafer”) obtained byforming, on a P type single crystal silicon wafer (semiconductorsubstrate), a P type Si epitaxial wafer (the epitaxial layer may be anSi-based epitaxial layer such as SiGe epitaxial layer) having animpurity concentration lower than that of the P type single crystalsilicon wafer will be described as one example. The wafer may be a bulkSi-based wafer as well as the epitaxial Si-based wafer. The substratestructure may be that obtained by forming an N type Si epitaxial layeror the like on a P type semiconductor substrate or forming an N type Siepitaxial layer, a P type Si epitaxial layer, or the like on an N typesemiconductor substrate. The structure of a semiconductor substrate maybe a P type or N type bulk wafer as well as the epitaxial wafer.Further, the structure of a semiconductor substrate may be an SOI waferas shown in Section 7 or the like as well the epitaxial wafer or bulkwafer.

As an element isolation structure in a wide region, a combined structure(which will hereinafter be called “DTI isolation”) of deep trenchisolation (DTI) and junction isolation will be shown as an example. Asan element isolation structure in a narrow region, shallow trenchisolation (STI) or an isolation structure based thereon (they will becalled “STI structure”, collectively) is used. The element isolationstructure in a wide region may however be junction isolation of varioustypes or “SOI isolation” using DTI isolation and SOI isolation incombination, as well as DTI isolation.

In general, a power IC (integrated circuit) has a plurality of various Ntype and P type power MOSFETs (or MISFETs) constituting a high breakdownvoltage circuit, more specifically, a high breakdown voltage transistor,N type and P type low breakdown voltage MISFETs constituting a CMOScontrol circuit or the like, a bipolar transistor, and the like. In thefollowing example, however, in order to avoid complication, mainly a Pchannel type LDMOSFET and each of N type and P type low breakdownvoltage MISFETs will be described specifically as an example. Thefollowing example can therefore be applied to not only a P channel typeLDMOSFET but also an N channel type LDMOSFET.

In the power IC or power system IC to be described next, a highbreakdown voltage circuit corresponds to various driver circuits,amplifier circuits, level shift circuits, various switching circuits,and the like, while a low breakdown voltage circuit corresponds to adigital or analogue control circuit that controls these circuits.

Further, a gate process of a high breakdown voltage device region and alow breakdown voltage device region will be described specifically witha gate first process as an example. It is needless to say that as a gateprocess of a low breakdown voltage device region, a gate last process oran intermediate process therebetween may be used.

A gate insulating film will hereinafter be described specifically whileusing, as an example thereof, a gate insulating film using mainly asilicon oxide film (a silicon oxynitride film or a composite film ofthem) obtained by thermal oxidation. It is however needless to say thata silicon oxide film, a silicon oxynitride film, a high dielectricconstant insulating film, or the like obtained using CVD (chemical vapordeposition) or using CVD and thermal oxidation in combination may beused.

A gate electrode will hereinafter be described specifically while usingmainly a polysilicon-based gate electrode as an example. It is needlessto say that a so-called metal gate electrode (including a composite filmwith a polysilicon-based gate electrode) may be used.

FIG. 1 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) for describing a method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication. FIG. 2 is a device cross-sectional view of a low breakdownvoltage device region during the wafer process (a hard mask primaryprocessing step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 3 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a step offorming a sidewall silicon oxide film-based insulating film forprocessing) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication. FIG. 4 is a device cross-sectional view of the highbreakdown voltage device region during the wafer process (a step offorming a sidewall insulating film for processing) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 5 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (an offset drain shallow trench etching step)for describing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 6 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a step of removing the sidewallinsulating film for processing) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 7 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (a step of etching a shallow trench of an elementisolation portion or the like) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 8 is a devicecross-sectional view of the low breakdown voltage device region duringthe wafer process (a step of etching a shallow trench of an elementisolation portion or the like) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 9 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (an inner wall oxide film formation step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 10 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (an inner wall oxide filmformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 11 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a buriedinsulating film formation step) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 12 is a devicecross-sectional view of the low breakdown voltage device region duringthe wafer process (a buried insulating film formation step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 13 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a CMP step) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 14 is adevice cross-sectional view of the low breakdown voltage device regionduring the wafer process (a CMP step) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 15 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (a buried insulating film etch-back step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 16 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a buried insulating filmetch-back step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 17 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a hardmask removal step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 18 is a device cross-sectional view of thelow breakdown voltage device region during the wafer process (a hardmask removal step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 19 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a gatepolysilicon film formation step) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 20 is a devicecross-sectional view of the low breakdown voltage device region duringthe wafer process (a gate polysilicon film formation step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 21 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a gate electrode processingstep) for describing the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication. FIG. 22 is a device cross-sectional view of the lowbreakdown voltage device region during the wafer process (a gateelectrode processing step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 23 is a device cross-sectional view of thelow breakdown voltage device region during the wafer process (a step ofintroducing an LDD region or the like) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 24 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (a gate sidewall formation step) for describing themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 25 is adevice cross-sectional view of the low breakdown voltage device regionduring the wafer process (a gate sidewall formation step) for describingthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 26 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (a P type high-concentration source-drainregion introduction step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 27 is a device cross-sectional view of thelow breakdown voltage device region during the wafer process (an N typeand P type high-concentration source-drain regions introduction step)for describing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 28 is a device cross-sectional view of the high breakdown voltagedevice region during the wafer process (a salicide step) for describingthe method of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 29 is adevice cross-sectional view of the low breakdown voltage device regionduring the wafer process (a salicide step) for describing the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 30 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (a premetal insulating layer formation step) fordescribing the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 31 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (a premetal insulating layerformation step) for describing the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. Based on these drawings, a main process of themethod of manufacturing a semiconductor integrated circuit deviceaccording to the present application will be described. In the examplesshown in FIGS. 1 and 2, FIGS. 7 and 8, FIGS. 9 and 10, FIGS. 11 and 12,FIGS. 13 and 14, FIGS. 15 and 16, FIGS. 17 and 18, FIGS. 19 and 20,FIGS. 21 and 22, FIGS. 24 and 25, FIGS. 28 and 29, and FIGS. 30 and 31,steps corresponding to each other are carried out simultaneously. Theymay however be selectively carried out separately as needed. In theexample shown in FIGS. 26 and 27, steps corresponding to each other arecarried out simultaneously, but when they are different in theconcentration of an impurity region or implantation energy, they may becarried out separately.

Based on FIGS. 1 and 2, steps until the hard mask processing step forthe formation of a shallow trench will be described briefly. Theintroduction order of an impurity region is only one example and can bechanged freely as needed.

A P type Si epitaxial wafer 1 is provided and as shown in FIG. 1, in ahigh breakdown voltage device region 11 (first region), a P type deepwell region 3 p which will be a P type offset drain region 23 p (P typedrift region) is introduced into a surface 1 a (main surface opposite toa back surface 1 b of a wafer 1) of a P type epitaxial region 1 e, forexample, by using conventional lithography and ion implantation incombination.

Next, as shown in FIG. 1, in the high breakdown voltage device region11, a P type well region 4 p which will be a P type low-concentrationdrain region 14 p is introduced into the surface 1 a of the P typeepitaxial region 1 e, for example, by using conventional lithography andion implantation in combination.

Next, as shown in FIG. 1, in the high breakdown voltage device region11, an N type well region 4 n which will be an N type body region 14 nis introduced into the surface 1 a of the P type epitaxial region 1 e,for example, by using conventional lithography and ion implantation incombination. At the same time, as shown in FIG. 2, in a low breakdownvoltage device region 12 (second region), an N type well region 4 n forthe formation of a P channel type transistor is introduced into thesurface 1 a of the P type epitaxial region 1 e, for example, by usingconventional lithography and ion implantation in combination.

Next, as shown in FIGS. 1 and 2, an underlying insulating film 5 whichwill be a gate insulating film 10 is formed on almost the entirety ofthe surface 1 a of the wafer 1. The term “almost” is used because suchan insulating is sometimes not formed (or once formed and then removed)around the wafer or in a region where the insulating film cannot beformed for a particular reason (which will equally apply hereinafter toa similar case). Preferred examples of the underlying insulating film 5include thermal oxide films (for example, a silicon oxide film) having athickness of about 8 nm.

Next, as shown in FIGS. 1 and 2, an underlying polysilicon film 6 isformed as a portion (underlying portion) of a hard mask film 9 on almostthe entirety of the surface 1 a of the wafer 1, for example, by CVD(chemical vapor deposition) (using, for example, a SH₄/N₂ gas or thelike as a film forming gas). The thickness of the underlying polysiliconfilm 6 is preferably, for example, about 20 nm. This underlyingpolysilicon film 6 contributes to a so-called self-aligned STI processin burying an interelement STI insulating film or the like.

Next, as shown in FIGS. 1 and 2, a silicon nitride-based hard mask film7 (for example, a silicon nitride film) is formed as a portion (mainportion) of the hard mask film 9 on almost the entirety of the surface 1a of the wafer 1, for example, by low-pressure CVD (using aSiH₂Cl₂/HN₃/N₂ gas or the like as a film forming gas). The thickness ofthe silicon nitride-based hard mask film 7 is preferably for exampleabout 130 nm.

Next, as shown in FIGS. 1 and 2, in the high breakdown voltage deviceregion 11, the hard mask film 9 is processed using conventionallithography and anisotropic dry etching in combination while using theunderlying insulating film 5 as an etching stopping layer to form anopening 8 (first opening). A gas used in anisotropic dry etching of thesilicon nitride-based hard mask film 7 is preferably, for example,SF₆/CHF₃. On the other hand, a gas used in anisotropic dry etching ofthe underlying polysilicon film 6 is preferably, for example, HBr/O₂.

Next, as shown in FIG. 3, a sidewall silicon oxide-based insulating film15 for processing is formed on almost the entirety of the surface 1 a ofthe wafer 1, for example, by CVD (using an O₃/TEOS gas or the like as afilm forming gas) or the like. The thickness of the sidewall siliconoxide-based insulating film 15 for processing is preferably, forexample, about 30 nm.

Next, as shown in FIG. 4, a sidewall insulating film 16 for processingis formed by etching back the sidewall silicon oxide-based insulatingfilm 15 for processing and the underlying insulating film 5 with thesemiconductor substrate as an etching stopper, for example, byanisotropic dry etching. The gas used in this anisotropic dry etching ispreferably, for example, C₄F₈/O₂/Ar. The width of the sidewallinsulating film 16 for processing is preferably, for example, about 30nm.

Next, as shown in FIG. 5, an offset drain shallow trench 21 (firstshallow trench) is formed in a semiconductor region surface 46 of thesurface 1 a of the wafer 1, for example, by anisotropic dry etching. Thegas used in this anisotropic dry etching is preferably, for example,HBr/O₂ and etching depth is preferably, for example, about 300 nm.

Next, as shown in FIG. 6, the sidewall insulating film 16 for processingand the underlying insulating film 5 lying therebelow are removed, forexample, by wet etching. The etchant to be used in this wet etching ispreferably, for example, a hydrofluoric acid-based silicon oxide filmetchant. Removal of the sidewall insulating film 16 for processing andthe underlying insulating film 5 lying therebelow is optional insofar asthey do not obstruct subsequent burying or the like and they may be leftas are. When they are left as are, the process becomes simpler. Whenthey are removed, a drain offset STI insulating film 25 (FIG. 17) canhave a uniform quality or the like.

Next, as shown in FIGS. 7 and 8, openings 18 a and 18 b (secondopenings) are formed in the hard mask film 9 and the underlyinginsulating film 5, for example, by using conventional lithography (usinga patterned shallow trench processing resist film 17 for an elementisolation portion or the like) and anisotropic dry etching incombination. Then, without any change, shallow trenches 22 a and 22 b(second shallow trenches) for an element isolation portion or the likeare formed in the semiconductor region surface 46 of the surface 1 a ofthe wafer 1. Then, the resist film 17 which becomes unnecessary isremoved, for example, by ashing. In this anisotropic dry etching, forexample, the following gas is used. A gas used for the siliconnitride-based hard mask film 7 is preferably, for example, SF₆/CHF₃;that for the underlying polysilicon film 6 is preferably, for example,HBr/O₂; that for the underlying insulating film 5 is preferably, forexample, CF₄/CHF₃; and that for the semiconductor substrate 1 ispreferably for example, HBr/O₂. The depth of the shallow trenches 22 aand 22 b is preferably, for example, about 300 nm, which is similar tothat of the offset drain shallow trench 21.

Next, as shown in FIGS. 9 and 10, an inner wall oxide film 19 is formedon at least an exposed portion of the semiconductor region surface 46 ofthe surface 1 a of the wafer 1, for example, by thermal oxidation. Thethickness of the inner wall oxide film 19 is preferably, for example,about 10 nm. As a method of the thermal oxidation, thermal oxidationtreatment or the like, for example, under reduced pressure atmosphere(mixed atmosphere containing oxygen and hydrogen as main components) ispreferred. As the method of thermal oxidation, conventional vaporatmosphere thermal oxidation method or another thermal oxidation methodmay be used as well as so-called in-situ vapor generation method.

Next, as shown in FIGS. 11 and 12, a silicon oxide-based insulating filmis formed as a buried insulating film 24 on almost the entire surface onthe surface 1 a side of the wafer 1, for example, by HDP-CVD (highdensity plasma chemical vapor deposition). The thickness of the buriedinsulating film 24 is preferably, for example, about 550 nm. A methodother than HDP-CVD may be used as the film formation method. Theopenings 8, 18 a, and 18 b in the hard mask film and the shallowtrenches 21, 22 a, and 22 b are filled with the buried insulating film24.

Next, as shown in FIGS. 13 and 14, the buried insulating film 24 outsidethe openings 8, 18 a, and 18 b and the shallow trenches 21, 22 a, and 22b in the hard mask film is removed, for example, by CMP (chemicalmechanical polishing) to planarize the surface 1 a.

Next, as shown in FIGS. 15 and 16, a silicon oxide-based insulating filmsuch as the buried insulating film 24 in the surface 1 a of the wafer 1is etched back by wet etching (for example, with a hydrofluoricacid-based etchant for etching of a silicon oxide-based insulating film)so as to leave the silicon oxide-based insulating film on the inner walloxide film 19. The thickness of the silicon oxide-based insulating filmwhich has remained after etch back is preferably, for example, about 15nm (thickness including the inner wall oxide film 19 is about 25 nm). Bythis etch back, the shallow trenches 22 a and 22 b (second shallowtrenches) for element isolation portion are filled with interelement STIinsulating films 26 a and 26 b. On the other hand, the offset drainshallow trench 21 (first shallow trench) is filled with a drain offsetSTI insulating film 25. As shown in FIG. 15, the drain offset STIinsulating film 25 is comprised of a main portion 25 c in and on theoffset drain shallow trench 21 and a drain side portion 25 d and asource side portion 25 s which are contiguous to the main portion andpresent outside the offset drain shallow trench 21. The thickness of thedrain side portion 25 d and the source side portion 25 s, that is, bothend portions 25 d and 25 s is thinner than the thickness of the mainportion 25 c.

As shown in FIGS. 17 and 18, the silicon nitride-based hard mask film 7(FIGS. 15 and 16) which is a main portion of the hard mask film 9, isselectively removed, for example, by wet etching (for example, with hotphosphoric acid).

Next, as shown in FIGS. 19 and 20, a gate polysilicon film 27 which willbe a main gate electrode film is formed on almost the entire surface onthe surface 1 a side of the wafer 1, for example, by CVD. This meansthat the underlying polysilicon film 6 and the gate polysilicon film 27together include a main portion of a gate electrode film. The thicknessof the gate polysilicon film 27 is preferably, for example, about 140nm.

Next, as shown in FIGS. 21 and 22, the gate polysilicon film 27 and theunderlying polysilicon film 6 are processed, for example, by usingconventional lithography and anisotropic dry etching in combination. Asa result, as shown in FIG. 21, a gate electrode 20 p (gate electrode ofa high breakdown voltage transistor) of a P channel type high breakdownvoltage LDMOSFET is formed from the upper portion of the gate insulatingfilm 10 in a source-side active region 31 (first active region) adjacentto the drain offset STI insulating film 25 to the upper portion of thedrain offset insulating film 25. On the other hand, as shown in FIG. 22,a gate electrode 40 p (gate electrode of a low breakdown voltagetransistor, a second gate electrode) of a P channel type low breakdownvoltage MISFET is formed on the gate insulating film 10 in an activeregion 51 p (second active region) adjacent to the shallow trench 22 b(second shallow trench) of an element isolation portion or the like.Further, as shown in FIG. 22, a gate electrode 40 n (gate electrode of alow breakdown voltage transistor) of an N channel low breakdown voltageMISFET is formed on the gate insulting film 10 in the active region 51n, similarly. The width (gate length) of the gate electrode 20 p dependson a technology node, but in the case where the low breakdown voltagetransistor has a gate length of about 80 nm, it is preferably, forexample, about 2.6 μm. The gate electrodes 40 n and 40 p have a width ofpreferably, for example, about 80 nm.

In FIGS. 21 and 22 and drawings thereafter, a residual film of theunderlying insulating film 5 on the active region not covered with thegate electrode or a thin-film surface oxide film similar to it such assacrificial oxide film for ion implantation is not shown to avoidcomplications unless otherwise required.

Next, as shown in FIG. 23, in the low breakdown voltage device region12, an N type LDD (lightly doped drain) region 32 n and a p type LDDregion 32 p are introduced successively, for example, by ionimplantation

Next, as shown in FIGS. 24 and 25, for example, similar to theabove-mentioned step (FIGS. 3 and 4), a gate sidewall insulating film 33(a silicon oxide-based insulating film, a silicon nitride-basedinsulating film, or a composite film thereof from the standpoint of amaterial) is formed around the gate electrodes 20 p, 40 n, and 40 p.

Next, as shown in FIGS. 26 and 27, a P type high-concentration drainregion 34 p, a P type high-concentration source region 35 p, and a Ptype high-concentration source drain region 36 p are introduced, forexample, by ion implantation. As shown in FIG. 27, an N typehigh-concentration source drain region 36 n is introduced, for example,by ion implantation. Needless to say, the above-mentioned ionimplantation may be carried out in any order.

Next, as shown in FIGS. 28 and 29, silicide films 37 d, 37 ds, 37 g, and37 s are formed, for example, by salicide process. The silicide filmsare preferably, for example, a cobalt silicide film. As the silicidefilm, a nickel silicide film, a platinum silicide film, a titaniumsalicide film, or another silicide film as well as the cobalt silicidefilm can be used.

Next, as shown in FIGS. 30 and 31, a silicon nitride-based premetalinsulating film 41 (for example, a silicon nitride film) is formed as anetch stop film or the like on almost the entire surface on the side ofthe surface 1 a of the wafer 1, for example, by CVD. Next, a siliconoxide-based premetal insulating film 42 (for example, a silicon oxidefilm) thicker than the silicon nitride-based premetal insulating film 41is formed on almost the entire surface on the silicon nitride-basedpremetal insulating film 41, for example, by CVD. Next, a contact hole47 is formed in the silicon oxide-based premetal insulating film 42 andthe silicon nitride-based premetal insulating film 41 and for example, atungsten plug 43 is buried in the contact hole. Then, a multilayeredcopper-based buried wiring, that is, damascene wiring layer or the likeis formed on the silicon oxide-based premetal insulating film 42 asneeded, followed by formation of an external coupling pad(aluminum-based pad, copper-based pad, or the like) on the uppermostlayer. If necessary, a bump electrode (solder bump, copper bump, silverbump, gold bump, or the like) is formed on the external coupling pad.The wafer 1 is then divided into individual chips 2 by dicing or thelike.

As described above, impact ionization or formation of divots can besuppressed by forming, as a final structure, a structure in which thedrain offset STI insulating film 25 (FIG. 30) in the high breakdownvoltage device region 11 extends to the active region. Due to the finalstructure in which the drain offset STI insulating film 25 (FIG. 30) inthe high breakdown voltage device region 11 (refer to, for example, FIG.30) extends to the active region, deterioration of a gate insulatingfilm caused by invasion of high energy carriers generated by impactionization into the end portion of the active region, which leads todeterioration in reliability, can be prevented. In addition, withoutdivots, deterioration in reliability due to the electric fieldconcentration at the end portion of the active region and undesiredthinning of the gate insulating film which will otherwise occur in theconventional STI process can be prevented.

On the other hand, as in the above-mentioned embodiment, when an SA-STI(self-aligned-STI) process is used in the low breakdown voltage deviceregion 12 (refer to, for example, FIG. 31), high integration and alsosuppression of divot formation can be achieved.

As in the above-mentioned embodiment, using an STI process in both thehigh breakdown voltage device region 11 (refer to, for example, FIG. 30)and the low breakdown voltage device region 12 (refer to, for example,FIG. 31) enables effective reduction in heat treatment time comparedwith combined use of a LOCOS process and an STI process.

This means that by using STI processes having respectively differentsystems for the drain offset STI insulating film 25 (FIG. 30) of thehigh breakdown voltage device region 11 (refer to, for example, FIG. 30)and another STI insulating film, the most suited processes can be usedfor these isolation insulating films, respectively. As a result, theseisolation insulating films can each have the most suited structure.

By using STI processes having respectively different systems for thedrain offset STI insulating film 25 (FIG. 30) of the high breakdownvoltage device region 11 (refer to, for example, FIG. 30) and the STIinsulating film of the low breakdown voltage device region 12 (refer to,for example, FIG. 31), the most suited processes can be used for theseisolation insulating films, respectively. As a result, these isolationinsulating films can each have the most suited structure. It is alsoeffective for miniaturization of the low breakdown voltage device region12 (refer to, for example, FIG. 31).

2. Description on a Modification Example (Modification Example 1:Additional Process to Isotropic Substrate Etching), in a FormationProcess of a Trench to be Filled with an Offset Drain IsolationInsulating Film, of the Method of Manufacturing a SemiconductorIntegrated Circuit Device According to First Embodiment of the PresentApplication (Mainly, FIG. 32)

The example described in this section is a modification example in whichthe trench etching step of the basic example described referring to FIG.5 in Section 1 has been modified. In the present example, the otherportion is similar to that described in Section 1 so that only adifferent portion will be described in principle.

FIG. 32 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (an additional isotropic etchingstep) following the step of FIG. 5 for describing a modification example(Modification Example 1), in hard mask, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. Based on this drawing, the modification example(Modification Example 1), in a formation process of a trench to befilled with an offset drain isolation insulating film, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application will be described. The stepsuntil the step of FIG. 4 are same so that a description is started fromthe step corresponding to FIG. 5.

In the trench etching step of FIG. 5, single anisotropic dry etchingstep is used. In this modification example, however, a two-stage step(or multi-stage step) comprised of anisotropic dry etching as a firststep and isotropic dry etching as a second step is used. This means thatin FIG. 5, after anisotropic dry etching is carried out as a first step,isotropic dry etching is performed as a second step as shown in FIG. 32.The etching depth of anisotropic dry etching as the first step ispreferably, for example, about 270 nm. The etching depth of isotropicdry etching as the second step is preferably, for example, about 30 nm.In this case, an overhang width Wo becomes about 30 nm. In this example,therefore, the width Wt of a trench (a first trench width) becomes widerthan the width Ws between sidewall insulating films for processing.Further, the bottom end portion of the offset drain shallow trench 21(first shallow trench) has a more rounded shape compared with the shapeshown in FIG. 5.

Steps after that, in other words, steps corresponding to those shown inFIGS. 6 to 31 are essentially the same.

As described above, in the example described in this section, the bottomcorner portion of the drain offset isolation trench of the highbreakdown voltage portion is rounded more than that in Section 1 becauseisotropic etching is added. Generation of hot carriers due to impactionization can be reduced by suppressing electric field concentration inthe vicinity of the bottom corner portion of the drain offset isolationtrench of the high breakdown voltage portion.

3. Description on a Modification Example (Modification Example 2:Process of Adding a Polysilicon Film to an Upper Layer of a Hard Mask),in Hard Mask, of the Method of Manufacturing a Semiconductor IntegratedCircuit Device According to First Embodiment of the Present Application(Mainly, FIGS. 33 to 36)

The example described in this section is a modification example of thebasic example described in Section 1. For example, the constitution ofthe hard mask film 9 shown in FIGS. 1 and 2 and the trench etching stepof FIG. 5 have been modified. The other portion is similar to thatdescribed in Section 1 so that only a different portion will bedescribed in principle.

In the low breakdown voltage device region 12, this modification exampleis similar to the above-mentioned embodiment except for the constitutionof the hard mask film 9 so that only the high breakdown voltage deviceregion 11 will hereinafter be described.

The example described in this section is a modification example of thebasic example described in Section 1 and at the same time, a furthermodification example of the modification example described in Section 2.It is needless to say that the example described in this section can beapplied not only to the basic example described in Section 1 but also toanother modification example.

FIG. 33 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) following the step of FIG. 1 for describing a modification example(Modification Example 2), in hard mask, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 34 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a step offorming a sidewall silicon oxide-based insulating film for processing)corresponding to the step of FIG. 3 for describing the modificationexample (Modification Example 2), in hard mask, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 35 is a devicecross-sectional view of the high breakdown voltage device region duringthe wafer process (a step of forming a sidewall insulating film forprocessing) corresponding to the step of FIG. 4 for describing themodification example (Modification Example 2), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 36 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (an offset drain shallow trench isotropicetching step) corresponding to the step of FIG. 5 for describing themodification example (Modification Example 2), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. Based on thesedrawings, the modification example (Modification Example 2), in hardmask, of the method of manufacturing a semiconductor integrated circuitdevice of First Embodiment of the present application will hereinafterbe described.

Steps of this modification example until the introduction of the N typewell region 4 n in the description referring to FIG. 1 are similar tothose of the basic example so that steps after completion of theintroduction step of the N type well region 4 n will hereinafter bedescribed. As shown in FIG. 33, an underlying insulating film 5 which isto be a gate insulating film 10 is formed on almost the entirety of thesurface 1 a of the wafer 1. The underlying insulating film 5 ispreferably, for example, a thermal oxide film (for example, a siliconoxide film) having a thickness of about 8 nm.

Next, as shown in FIG. 33, an underlying polysilicon film 6 is formed asa portion (underlying portion) of the hard mask film 9 on almost theentirety of the surface 1 a of the wafer 1, for example, by CVD (using,for example, SH₄/N₂ as a film forming gas). The thickness of theunderlying polysilicon film 6 is preferably, for example, about 20 nm.This underlying polysilicon film 6 contributes to a so-calledself-aligned STI process used in burying an interelement STI insulatingfilm or the like.

Next, as shown in FIG. 33, a silicon nitride-based hard mask film 7 (forexample, a silicon nitride film) is formed as a portion (main portion)of the hard mask film 9 on almost the entirety of the surface 1 a of thewafer 1, for example, by low-pressure CVD (using, for example,SiH₂Cl₂/HN₃/N₂ as a film forming gas). The thickness of the siliconnitride-based hard mask film 7 is preferably, for example, 90 nm.

Next, as shown in FIG. 33, a hard mask intermediate silicon oxide-basedinsulating film 29 is formed on almost the entire surface on the siliconnitride-based hard mask film 7, for example, by CVD (using, for example,O₃/TEOS as a gas). The thickness of the hard mask intermediate siliconoxide-based insulating film 29 is preferably, for example, about 10 nm.

Next, as shown in FIG. 33, a hard mask upper-half polysilicon film 28 isformed on almost the entire surface on the hard mask intermediatesilicon oxide-based insulating film 29, for example, by CVD. Thethickness of the hard mask upper-half polysilicon film 28 is preferably,for example, about 250 nm.

Next, as shown in FIG. 33, with the films lying immediately thereunderas an etching stopping layer, films constituting the hard mask film 9are processed, respectively, by using conventional lithography andanisotropic dry etching in combination to form an opening 8 (firstopening). A gas used in anisotropic dry etching of the hard maskupper-half polysilicon film 28 is preferably, for example, HBr/O₂.Similarly, a gas used in anisotropic dry etching of the hard maskintermediate silicon oxide-based insulating film 29 is preferably, forexample, CF₄/CHF₃. Similarly, a gas used in anisotropic dry etching ofthe silicon nitride-based hard mask 7 is preferably, for example,SF₆/CHF₃. A gas used in anisotropic dry etching of the underlyingpolysilicon film 6 is preferably, for example, HBr/O₂.

Next, as shown in FIG. 34, a sidewall silicon oxide-based insulatingfilm 15 for processing is formed on almost the entirety of the surface 1a of the wafer 1, for example, by CVD (using, for example, O₃/TEOS as afilm forming gas). The thickness of the sidewall silicon oxide-basedinsulating film 15 for processing is preferably, for example, about 330nm.

Next, as shown in FIG. 35, a sidewall insulating film 16 for processingis formed by etching back the sidewall silicon oxide-based insulatingfilm 15 for processing and the underlying insulating film 5 byanisotropic dry etching while using the semiconductor substrate as anetching stopper. A gas used in this anisotropic dry etching ispreferably, for example, C₄F₈/O₂/Ar. The width of the sidewallinsulating film 16 for processing is preferably, for example, about 330nm.

Next, as shown in FIG. 36, in the high breakdown voltage device region11, an offset drain shallow trench 21 (first shallow trench) is formedin a semiconductor region surface 46 on the side of the surface 1 a ofthe wafer 1, for example, by isotropic dry etching. A gas used in thisisotropic dry etching is preferably, for example, CF₄/O₂. At the time ofthis etching, variation in trench etching can be reduced, for example,by detecting an etching endpoint while using disappearance of the hardmask upper-half polysilicon film 28 shown in FIG. 35 as a trigger.

An etching depth at this etching is preferably, for example, 300 nm. Awidth Wr of a portion of the substrate remaining below the sidewall ispreferably, for example, 30 nm. In this example, a trench width Wt(width of first trench) becomes wider than a width Ws between thesidewall insulating films for processing. The offset drain shallowtrench 21 (first shallow trench) has a bottom end portion rounder thanthat of FIG. 32.

Steps after that, that is, steps from FIGS. 6 to 31 are essentiallysimilar to those of the basic example.

As described above, formation of an additional film comprised of apolysilicon film (upper layer), a silicon oxide-based insulating film(lower layer), and the like on an upper portion of the hard maskstructure described in Section 1 makes it possible to form a drainoffset isolation trench in a high breakdown voltage portion by usingonly isotropic etching mainly.

Further, this makes it possible to determine the etching endpoint at thetime of etching of a drain offset isolation trench in the high breakdownvoltage portion while using disappearance of the upper layer polysiliconfilm of the hard mask (for example, monitoring a gas type exhausted byan etching reaction of silicon) as a trigger and facilitate reduction invariation of a trench depth. In this case, since the drain offsetisolation trench in the high breakdown voltage portion has almost noperpendicular portion, the structure thus obtained is ideal forsuppressing impact ionization.

When importance is given to reduction in variation of a trench depth,anisotropic etching may be employed for the first half etching as inSection 2.

4. Description on a Modification Example (Modification Example 3:Non-Self-Aligned STI Process), in Hard Mask, of the Method ofManufacturing a Semiconductor Integrated Circuit Device According toFirst Embodiment of the Present Application (Mainly, FIGS. 37 to 43)

The example described in this section is a modification example in whichthe constitution of the hard mask film 9 (FIG. 1) of the basic exampledescribed in Section 1 has been modified. The other portions aretherefore just the same as those described in Section 1 so that onlydifferent portions will be described in principle.

In addition, the example described in this section is a modificationexample of the basic example described in Section 1 and at the sametime, a further modification example of the modification examplesdescribed in Sections 2 and 3. It is needless to say that the exampledescribed in this Section can be applied not only to the basic exampledescribed in Section 1 but also to another modification example.

FIG. 37 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask primary processingstep) corresponding to the step of FIG. 1 for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 38 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (a hard mask removal step) corresponding to thestep of FIG. 17 for describing the modification example (ModificationExample 3), in hard mask, of the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication. FIG. 39 is a device cross-sectional view of a low breakdownvoltage device region during the wafer process (a hard mask removalstep) corresponding to the step of FIG. 18 (FIG. 38) for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 40 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (an underlying insulating film removal step)for describing the modification example (Modification Example 3), inhard mask, of the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment of the present application.FIG. 41 is a device cross-sectional view of the low breakdown voltagedevice region during the wafer process (an underlying insulating filmremoval step) corresponding to the step of FIG. 40 for describing themodification example (Modification Example 3), in hard mask, of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 42 is adevice cross-sectional view of the high breakdown voltage device regionduring the wafer process (a gate polysilicon film formation step)corresponding to the step of FIG. 19 for describing the modificationexample (Modification Example 3), in hard mask, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application. FIG. 43 is a devicecross-sectional view of the low breakdown voltage device region duringthe wafer process (a gate polysilicon film formation step) correspondingto the step of FIG. 20 (FIG. 42) for describing the modification example(Modification Example 3), in hard mask, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. Based on these drawings, the modificationexample (Modification Example 3), in hard mask, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application will be described.

In the example of FIG. 1, the underlying insulating film 5 (gateinsulating film 10) and the silicon nitride-based hard mask film 7 havetherebetween the underlying polysilicon film 6, while in the presentmodification example, as shown in FIG. 37, the hard mask film 9 does nothave the underlying polysilicon film 6 as a portion thereof. This meansthat an underlying insulating film 5 (not a gate insulating film) has asilicon nitride-based hard mask 7 directly thereon. The process of thepresent modification example corresponding to FIG. 1 is therefore asdescribed below. Steps until introduction of the N type well region 4 ndescribed referring to FIG. 1 are the same so that a description will bestarted from a step after completion of the introduction step of the Ntype well region 4 n.

Described specifically, an underlying insulating film 5 is formed onalmost the entirety of the surface 1 a of the wafer 1 as shown in FIG.37. The underlying insulating film 5 is preferably, for example, athermal oxide film (for example, a silicon oxide film) having athickness of about 10 nm.

Next, as shown in FIG. 37, a silicon nitride-based hard mask film 7 (forexample, a silicon nitride film) is formed as a portion (main portion)of the hard mask film 9 on almost the entirety of the surface 1 a of thewafer 1, for example, by low-pressure CVD (using, for example,SiH₂Cl₂/HN₃/N₂ as a film forming gas). The thickness of the siliconnitride-based hard mask film 7 is preferably, for example, 130 nm.

Next, as shown in FIG. 37, in the high breakdown voltage device region11, the hard mask film 9 is processed to form an opening 8 (firstopening) by using conventional lithography and anisotropic dry etchingin combination and using the underlying insulating film 5 as an etchingstopper layer. A gas used for anisotropic dry etching of the siliconnitride-based hard mask film 7 is preferably, for example, SF₆/CHF₃.

Steps after that are essentially the same as those of FIGS. 2 to 16 sothat the description will be continued from the steps after those ofFIGS. 17 and 18. FIGS. 38 and 39 show the view after removal of the hardmask film 9.

Next, as shown in FIGS. 40 and 41, the underlying insulating film 5(refer to FIGS. 17 and 18) is removed, for example, by wet etching(with, for example, a hydrofluoric acid-based silicon oxide filmetchant).

Next, as shown in FIGS. 42 and 43, a gate insulating film 10 (forexample, a silicon oxide film, an oxynitride film, or a composite filmthereof) is formed on at least a semiconductor region surface 46 inactive regions 31, 48, 51 n, and 51 p on the side of the surface 1 a ofthe wafer 1, for example, by thermal oxidation (including oxynitriding).The thickness of the gate insulating film 10 is preferably, for example,8 nm.

Next, as shown in FIGS. 42 and 43, a gate polysilicon film 27 is formedon almost the entire surface on the side of the surface 1 a of the wafer1, for example, by CVD. The thickness of the gate polysilicon film 27 ispreferably, for example, about 160 nm.

The process thereafter is essentially the same as that described in fromFIGS. 21 to 31.

As described above, in all the examples described in Sections 1 to 3(and also, examples described later in Section 5 and 6), an SA-STIprocess is employed as the STI process. In the example described in thisSection, on the other hand, an N-STI (normal STI) is employed. In thiscase, defects such as divots may be formed in the upper side portion ofthe STI insulating film (normal STI insulating film) other than thedrain offset isolation insulating film in the high breakdown voltageportion. A high voltage is not applied to the normal STI insulating filmso that even in this case, problems occur relatively infrequently. Sucha process therefore can reduce a production cost further compared withthe SA-STI process.

5. Description on a Modification Example (Modification Example 4:Hydrogen Annealing Additional Process), in Corner Rounding of a Trenchto be Filled with an Offset Drain Isolation Insulating Film, of theMethod of Manufacturing a Semiconductor Integrated Circuit DeviceAccording to First Embodiment of the Present Application (Mainly, FIG.44)

The example described in this section is a modification example in astep between the steps of the basic example described in Section 1referring to FIGS. 6 and 7. The other steps are just the same as thosedescribed in Section 1 so that in this section, only a different portionwill be described in principle.

The example described in this section is a modification example of thebasic example described in Section 1 and at the same time, a furthermodification example of the respective modification examples describedin Sections 2 to 4. It is needless to say that the example described inthis section can be applied not only to the basic example described inSection 1 but also to the other modification examples.

FIG. 44 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a step of removing the sidewallinsulating film for processing) corresponding to the step of FIG. 6 fordescribing a modification example (Modification Example 4), in cornerrounding of a trench to be filled with an offset drain isolationinsulating film, of the method of manufacturing a semiconductorintegrated circuit device according to First Embodiment of the presentapplication. Based on this drawing, the modification example(Modification Example 4), in corner rounding of a trench to be filledwith an offset drain isolation insulating film, of the method ofmanufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application will be described.

In this example, an additional step is inserted between the steps of thebasic examples described in FIGS. 6 and 7. As shown in FIG. 44, thebottom end portion of a trench such as the offset drain shallow trench21 (first shallow trench) or the like is rounded, for example, bysubjecting the wafer 1 on the side of the surface 1 a tohigh-temperature annealing treatment. The high-temperature annealingtreatment is carried out preferably, for example, under the followingconditions: atmosphere: hydrogen atmosphere (atmospheric pressure: forexample, about 5 kPa), temperature: 1000° C., and treatment time: about3 minutes.

As described above, in this example, a trench to be filled with anoffset drain isolation insulating film is rounded at the corner thereof,for example, by carrying out high-temperature annealing immediatelyafter trench etching and thereby accelerating re-arrangement of siliconatoms.

This contributes to reduction in impact ionization in the vicinity ofthe corner of the trench to be buried with an offset drain isolationinsulating film.

6. Description on a Modification Example (Modification Example 5: STITrench Simultaneous Process for Portions Including an Offset Portion),in a Formation Process of a Trench to be Filled with an Offset DrainIsolation Insulating Film, in the Method of Manufacturing aSemiconductor Integrated Circuit Device According to First Embodiment ofthe Present Application (Mainly, FIGS. 45 to 48)

The example described in this section is a modification example of theprocess of the basic example described in Section 1 referring to FIGS.5, 6, 7, and 8. The other steps are just the same as those described inSection 1 so that in this section, only a different portion will bedescribed in principle.

The example described in this section is a modification example of thebasic example described in Section 1 and at the same time, a furthermodification example of the respective modification examples describedin Sections 2 to 5. It is needless to say that the example described inthis section can be applied not only to the basic example described inSection 1 but also to the other modification examples.

FIG. 45 is a device cross-sectional view of a high breakdown voltagedevice region during a wafer process (a hard mask secondary processingstep) corresponding to the step of FIG. 7 (first half part) fordescribing the modification example (Modification Example 5), in aformation process of a trench to be filled with an offset drainisolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 46 is a device cross-sectional view of alow breakdown voltage device region during the wafer process (a hardmask secondary processing step) corresponding to the step of FIG. 45 fordescribing the modification example (Modification Example 5), in aformation process of a trench to be filled with an offset drainisolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 47 is a device cross-sectional view of thehigh breakdown voltage device region during the wafer process (a shallowtrench simultaneous etching step) corresponding to the step of FIG. 7(latter half part) for describing the modification example (ModificationExample 5), in a formation process of a trench to be filled with anoffset drain isolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. FIG. 48 is a device cross-sectional view of thelow breakdown voltage device region during the wafer process (a shallowtrench simultaneous etching step) corresponding to the step of FIG. 47for describing the modification example (Modification Example 5), in aformation process of a trench to be filled with an offset drainisolation insulating film, of the method of manufacturing asemiconductor integrated circuit device according to First Embodiment ofthe present application. Based on these drawings, the modificationexample (Modification Example 5), in a formation process of a trench tobe filled with an offset drain isolation insulating film, of the methodof manufacturing a semiconductor integrated circuit device according toFirst Embodiment of the present application will be described.

In FIGS. 5, 6, 7, and 8, the shallow trenches 22 a and 22 b (secondshallow trenches) of the element isolation portion and the like areetched while having the shallow trench processing resist film 17 of theelement isolation portion and the like. In addition, the offset drainshallow trench 21 (first shallow trench) and the shallow trenches 22 aand 22 b (second shallow trenches) of the element isolation portion andthe like are etched separately.

In this example, on the other hand, after formation of openings 18 a and18 b (second openings) of the hard mask film in the hard mask film 9 bymaking use of the shallow trench processing resist film 17, the shallowtrench processing resist film 17 is removed. Then, etching of theshallow trenches 21, 22 a, and 22 b are performed simultaneously.Described specifically, it is performed as follows. Steps describedreferring to FIGS. 1 to 6 and 9 to 31 are essentially the same so thatonly steps corresponding to FIGS. 5, 6, 7, and 8 will next be described.

As shown in FIGS. 45 and 46, openings 18 a and 18 b (second openings)are formed in the hard mask film 9 and the underlying insulating film 5by using conventional lithography (using a patterned shallow trenchprocessing resist film 17 of the element isolation portion and the like)and anisotropic dry etching in combination. A gas used in thisanisotropic dry etching is, for example, as follows. The gas used inetching of the silicon nitride-based hard mask film 7 is preferably, forexample, SF₆/CHF₃, that used for etching of the underlying polysiliconfilm 6 is preferably, for example, HBr/O₂, and that used for etching ofthe underlying insulating film 5 is preferably, for example, CF₄/CHF₃.The resist film 17 which becomes unnecessary is then removed, forexample, by ashing.

Next, as shown in FIGS. 47 and 48, shallow trenches 21, 22 a, and 22 bare then formed in the semiconductor region surface 46 of the surface 1a of the wafer 1, for example, by anisotropic dry etching. A gas to beused in this anisotropic dry etching is preferably, for example, HBr/O₂.The depth of the shallow trenches 21, 22 a, and 22 b is preferably, forexample, about 300 nm.

As described above, in the example shown in any of Sections 1 to 5,etching steps for the trench to be filled with a drain offset isolationinsulating film and another trench to be filled with an STI insulatingfilm in the high breakdown voltage portion are performed separately,while in the example of this section, these etching steps are performedsimultaneously to simplify the process.

The surface of the wafer becomes more flat in this example compared withthat shown in FIGS. 7 and 8, which is advantageous because it enablesthinning of a resist and improvement in the processing accuracy of thelow breakdown voltage device region 11 (FIG. 46).

7. Complementary Description and General Consideration on theEmbodiments (Including the Modification Examples) (Mainly, FIGS. 49 to54)

FIG. 49 is a process block flow chart for describing the outline of themethod of manufacturing a semiconductor integrated circuit deviceaccording to First Embodiment of the present application. FIG. 50 is awhole chip top view showing one example of a chip layout in FirstEmbodiment (including modification examples) of the present application.FIG. 51 is a schematic cross-sectional view (DTI isolation structure) ofa device corresponding to the A-B cross-section of FIG. 50 showing oneexample of an element isolation structure and the like in FirstEmbodiment (including modification examples) of the present application.FIGS. 1, 3 to 7, 9, 11, 13, 15, 17, 19, 21, 24, 26, 28, and 30correspond to the cross-section cutout portion R3 of the high breakdownvoltage device region of FIG. 51, while FIGS. 2, 8, 10, 12, 14, 16, 18,20, 22, 23, 25, 27, 29 and 31 correspond to the cross-section cutoutportion R4 of the low breakdown voltage device region of FIG. 51. FIG.52 is an enlarged chip top view of an upper-surface cutout portion R1 ofthe high breakdown voltage region shown in FIG. 50. FIG. 53 is anenlarged chip top view of an upper-surface cutout portion R2 of the lowbreakdown voltage region shown in FIG. 50. FIG. 54 is a schematiccross-sectional view (DTI & SOI isolation structures) of a devicecorresponding to the A-B cross-section of FIG. 50 showing anotherexample of the element isolation structure and the like in FirstEmbodiment (including modification examples) of the present application.Based on these drawings, complementary description and generalconsideration on the embodiment (including the modification examples)will be performed.

(1) Complementary Description and Consideration on the Problems of theTechnology Used in First Embodiment (Including Modification Examples)

As described above, in the high breakdown voltage MOSFET and the like(for example, LDMOSFET), using a LOCOS field insulating film or the likefor element isolation or another isolation prolongs treatment steps andthereby increases a production cost. Present inventors have revealedthat using an STI field insulating film or the like, on the other hand,generates high energy electrons due to impact ionization in the vicinityof the bottom corner portion of a drain isolation insulating film andthe high breakdown voltage MOSFET or the like thus obtained hasdeteriorated reliability. Such a tendency is particularly marked in ahigh breakdown voltage P type LDMOSFET.

It is the common practice to use, in a 90-nm generation power integratedcircuit (device obtained by integrating a power MOSFET, CMISFET, bipolartransistor, and the like if necessary), a LOCOS structure for a highbreakdown voltage portion and an STI structure for a low breakdownvoltage portion. Investigation by the present inventors has howeverrevealed that since the LOCOS structure includes a heat treatment stepwhich requires a long treatment time, using this structure isdisadvantageous in cost.

When an STI isolation structure or the like is used simply for a highbreakdown voltage portion, however, a high breakdown voltage transistorsuch as LDMOSFET has deteriorated reliability due to fracture of a gateinsulating film on a drain side. As described above, this tendency isparticularly marked in a high breakdown voltage P type LDMOSFET. Asdescribed above, reasons of it are as follows: (a) generation of hotcarriers due to impact ionization in the vicinity of the bottom cornerportion of a drain offset isolation insulating film; and (b) substantialthinning of a gate insulating film and electric field concentration dueto divots at the upper side of a drain-side isolation insulating film.

With regard to the reason (a), it has been revealed by simulation andthe like that generation of hot carriers can be reduced by rounding thebottom corner portion of the drain offset isolation insulating film, inother words, rounding the corner portion of the bottom of the trench atthis portion.

With regard to the reason (b), it is presumed that generation of divotscan be suppressed by using a structure or process which does not causedivots and the like. As a countermeasure against it, an SA-STI structureis effective, but its advantage is presumed to be relatively small incost performance because the LOCOS structure can originally overcome theproblems (a) and (b).

The above-mentioned embodiment (including modification examples) hastherefore a device structure and process capable of suppressinggeneration of divots and the like whether or not it uses an SA-STIstructure. The above-mentioned embodiment (including modificationexamples) makes various devices for rounding the bottom corner portionof a trench in order to overcome the problem (a).

(2) Description on the Outline of the Method of Manufacturing aSemiconductor Integrated Circuit Device According to First Embodiment(Mainly FIG. 49)

The outline of the method of manufacturing a semiconductor integratedcircuit device according to First Embodiment includes the followingsteps as shown in FIG. 49. Described specifically, included are (a) astep of forming a hard mask film on a first main surface of asemiconductor wafer and forming a first opening in the hard mask film ina first region on the first main surface (hard mask primary processingstep 101); (b) a step of forming a sidewall insulating film on the sidesurface of the hard mask film of the first opening (sidewall formationstep 102); (c) a step of forming a first shallow trench in asemiconductor region surface of the first main surface in the firstopening with the hard mask film and the sidewall insulating film as amask; (d) after the step (c), a step of oxidizing at least an exposedportion of the inner surface of the first shallow trench and thesemiconductor region surface on the first main surface in the firstopening (oxidation step 104 of inner wall and the like); (e) after thestep (d), burying the first shallow trench and the first opening with aninsulating film (insulating film burying step 105); (f) after the step(e), a step of removing the insulating film outside the first shallowtrench so as to leave the insulating film outside the first shallowtrench in the first opening and thereby forming a drain offset STIinsulating film inside and outside the first shallow trench (buriedinsulating film removal step 106); and (g) after the step (f), a step offorming a first gate electrode from an upper portion of the gateinsulating film in a first active region contiguous to the drain offsetSTI insulating film to an upper portion of the drain offset insulatingfilm (gate electrode formation step).

The high breakdown voltage MOSFET obtained using the above method canhave improved reliability.

One of the characteristics of the semiconductor device according to theabove embodiment is that it uses an STI structure as the isolationstructure (that is, the drain offset STI insulating film) in the drainoffset region of the high breakdown voltage portion. This makes itpossible to effectively decrease the heat treatment time inmanufacturing the device.

The following are the other characteristics of the process or structureof the manufacturing method according to the above embodiment (includingmodification examples) and the device manufactured thereby (thefollowing characteristics can be used either singly or in combination).(i) Drain offset isolation (drain offset STI insulating film) in thehigh breakdown voltage portion and element-element isolation in the CMOSlow breakdown voltage device region each use an STI structure. (ii) Inaddition, the isolation oxide film for drain offset isolation in thehigh breakdown voltage portion extends (elongates) in the direction ofthe active region. (iii) Further, the drain offset isolation (drainoffset STI insulating film) has, at the bottom corner portion thereof, around structure. This means that it has, at the bottom end portion ofthe trench, a round structure.

The mechanism of them will next be described briefly. Since hot carriersdue to impact ionization are likely to travel along the sidewall of theisolation oxide film so that the gate insulating film at the end portionof the active region is likely to be broken. When the isolation oxidefilm extends in the direction of the active region, on the other hand, agate breakdown voltage is improved because of the presence of theisolation oxide film having a certain thickness on the sidewall of theisolation oxide film.

In this structure (structure of drain offset STI insulating film), theisolation oxide film has no divots at the upper-end side portion of theisolation oxide film so that the gate insulating film does not becomethin at the end portion of the active region and similarly, a gatebreakdown voltage is improved.

Further, the rounded bottom corner portion of the drain offsetisolation, that is, the rounded bottom end portion of the trench thereatis effective for suppressing impact ionization due to field effectconcentration at the isolation corner portion.

(3) Description on One Example of the Chip Layout of First Embodiment(Including Modification Examples) (Mainly, FIG. 50)

One example of the chip layout of First Embodiment (includingmodification examples) is shown in FIG. 50. As shown in FIG. 50, asemiconductor chip 2 has, on the surface 1 a thereof, for example, ahigh breakdown voltage device region 11 (first region) and a lowbreakdown voltage device region 12 (second region), isolated from eachother, for example, by DTI (deep trench isolation) regions 38 a and 38b, that is, deep trench isolation regions. The high breakdown voltagedevice region 11 has, for example, a high breakdown voltage device. Thelow breakdown voltage device region 12 has, on the other hand, forexample, a CMIS control circuit such as CMIS logic circuit and CMISanalogue circuit, each comprised of a low breakdown voltage devicehaving a breakdown voltage lower than that of the high breakdown voltagedevice.

(4) Description on a Global Specific Example 1 (Deep Trench Isolation)of the Chip Cross-Section of First Embodiment (Including ModificationExamples) (Mainly, FIG. 51)

Next, one example of the A-B cross-section of FIG. 50 is shown in FIG.51. The cross-section cutout portion R3 of the high breakdown voltagedevice region of FIG. 51 corresponds to FIGS. 1, 3 to 7, 9, 11, 13, 15,17, 19, 21, 24, 26, 28, 30, 33-38, 40, 42, 45, and 47.

The DTI (deep trench isolation) structure described below is typicallyobtained by covering the inner surface of a trench having a relativelynarrow width with a silicon oxide-based insulating film or the like andfilling the remaining space with polysilicon or the like. The DTIstructure is advantageous in a relatively high integration degree, butneedless to say, it is not essential. Further, it is needless to saythat the structure shown here is only one example and there are variousmodifications of it.

As shown in FIG. 51, for example, a P type semiconductor substrate 1 s(single crystal silicon semiconductor substrate layer) of asemiconductor chip 2 has, on the side of a surface 1 a, for example, a Ptype epitaxial region 1 e (P type epitaxial layer) having aconcentration lower than that of the substrate.

First, the high breakdown voltage device region 11 will be describedmainly. The P type semiconductor substrate 1 s and the P type epitaxialregion 1 e have therebetween a buried N type region 39 for electricalisolation or the like. A DTI region 38 a reaches the P typesemiconductor substrate 1 s (also a DTI region 38 b reaches it) andconstitutes a portion of an isolation structure. The P type epitaxialregion 1 e has, in and over a semiconductor region surface, variouselement regions of a P channel type high breakdown voltage LDMOSFET(Qhp). Described specifically, the semiconductor region surface has, forexample, an N type body region 14 n comprised of an N type well region 4n and a P type offset drain region 23 p comprised of a P type deep wellregion 3 p. Further, the N type body region 14 n has, in the surfacethereof, a P type high-concentration source region 35 p and the P typeoffset drain region 23 p has, in the surface thereof, a P typehigh-concentration drain region 34 p. The P type high-concentrationdrain region 34 p and the P type high-concentration source region 35 phave, in the semiconductor region surface therebetween, a drain offsetSTI insulating film 25. The P channel type high breakdown voltageLDMOSFET (Qhp) has, in the semiconductor region surface at the peripherythereof, an interelement STI insulating film 26 a. The N type bodyregion 14 n has, in the surface thereof, an N type body contact region44 n. Still further, the semiconductor region surface has thereon a gateelectrode 20 p via the gate insulating film 10.

Next, the low breakdown voltage device region 12 will be describedmainly. The P type epitaxial region 1 e has, in and over a semiconductorregion surface, various element regions of an N channel type lowbreakdown voltage MISFET (Qcn) and a P channel type low breakdownvoltage MISFET (Qcp). Described specifically, the semiconductor regionsurface has therein, for example, an N type well region 4 n constitutingthe main part of the P channel type low breakdown voltage MISFET (Qcp)and this well region has, in the surface thereof, P typehigh-concentration source drain regions 36 p of the P channel type lowbreakdown voltage MISFET (Qcp). On the other hand, the P type epitaxialregion 1 e has, on the surface thereof, N type high-concentration sourcedrain regions 36 n of the N channel type low breakdown voltage MISFET(Qcn). The P type high-concentration source drain regions 36 p have, onthe semiconductor region surface therebetween, a gate electrode 40 p viathe gate insulating film 10. The N type high-concentration source drainregions 36 n have, on the semiconductor region surface therebetween, agate electrode 40 n via the gate insulating film 10. Further, the Pchannel type low breakdown voltage MISFET (Qcp) and the N channel typelow breakdown voltage MISFET (Qcn) have, in the semiconductor regionsurface therebetween and in the semiconductor region surface at theperiphery thereof, an interelement STI insulating film 26 b.

(5) Description on One Example of a Planar Structure of a P TypeLDMOSFET (Lateral P Channel Power MOSFET) of First Embodiment (IncludingModification Examples) (Mainly, FIG. 52)

An enlarged plan view of the upper surface cutout portion R1 of the highbreakdown voltage device region in FIG. 50 is shown in FIG. 52. FIGS. 1,3 to 7, 9, 11, 13, 15, 17, 19, 21, 24, 26, 28, 30, 33 to 38, 40, 42, 45,and 47 are cross-sectional views corresponding to the C-D cross-sectionof FIG. 52.

As shown in FIG. 52, when the main element portions of the P channeltype high breakdown voltage LDMOSFET (Qhp) are viewed two-dimensionally,they have a cyclic or a multiple connecting structure. Describedspecifically, in this example, the drain offset STI insulating film 25,the source-side active region 31 (first active region), the gateelectrode 20 p of the P channel type high breakdown voltage LDMOSFET,the P type high-concentration source region 35 p, the interelement STIinsulating film 26 a, and the like have a cyclic structure (multipleconnecting structure) when viewed two-dimensionally.

In this example, however, the P type high-concentration drain region 34p and the like located at the center portion has a single connectingstructure when viewed two dimensionally.

In other words, the main element portions of the P channel type highbreakdown voltage LDMOSFET (Qhp) constituting a cyclic structure haveessentially, for example, a cross-section as shown in FIG. 30 over theentire circumference of the cyclic structure. Such a cyclic structure orthe like is not essential, but it simplifies the device structure andfurther, is effective for preventing undesirable reduction in breakdownvoltage.

(6) Description on One Example of the Planar Structure of a Core CMISFETof First Embodiment (Including Modification Examples) (Mainly, FIG. 53)

An enlarged plan view of the upper surface cutout portion R2 of the lowbreakdown voltage device region of FIG. 50 is shown in FIG. 53. FIGS. 2,8, 10, 12, 14, 16, 18, 20, 22, 23, 25, 27, 29, 31, 39, 41, 43, 46, and48 are cross-sectional views corresponding to the E-F cross-section ofFIG. 53.

As FIG. 53, the interelement STI insulating film 26 b has therein (in aregion surrounded therewith), active regions 51 n and 51 p. The activeregion 51 n has therein the gate electrode 40 n of the N channel typelow breakdown voltage MISFET and it is located so as to cross the activeregion longitudinally. The region 51 p has therein the gate electrode 40p of the P channel type low breakdown voltage MISFET and it is locatedso as to cross the region longitudinally. The gate electrodes 40 n and40 p have, at the periphery thereof, the gate sidewall insulating film33 and the gate electrodes 40 n and 40 p have, on both sides thereof,the N type high-concentration source drain region 36 n and the P typehigh-concentration source drain region 36 p.

(7) Description on Global Specific Example 2 (SOI Isolation) of the ChipCross-Section of First Embodiment (Including Modification Examples)(Mainly, FIG. 54)

As the global structure of the chip cross-section of First Embodiment(including modification examples), various structures can be used aswell as that shown in FIG. 51. An example using SOI isolation is shownin FIG. 54. This example is a modification example of FIG. 51 and only adifference will be shown below in principle.

In the example of FIG. 51, electrical isolation in the high breakdownvoltage device region 11 is achieved by making use of the buried N typeregion 39 and the like. In the present example, on the other hand, asshown in FIG. 54, the buried N type region 39 is replaced by a buriedinsulating film 45 which is provided on almost the entire surfacebetween the P type semiconductor substrate layer 1 s and the P typeepitaxial region 1 e. This means that DTI regions 38 a and 38 b (deeptrench isolation regions) reach the buried insulating film 45 and theburied insulating film 45 and the DTI regions 38 a and 38 b (deep trenchisolation regions) reach the buried insulating film 45 and the buriedinsulating film 45 and the DTI regions 38 a and 38 b include anisolation structure. Almost the whole region on this isolation structureis an SOI region, in other words, has an SOI structure. The term“almost” is used because a portion of this region is sometimes used as abulk region.

8. Summary

The invention made by the present inventors has been describedspecifically based on the embodiment. It is needless to say that thepresent invention is not limited to or by it but can be changed withoutdeparting from the gist of the invention.

For example, in the above embodiment, the multilayer wiring has beendescribed specifically with a copper-based buried wiring as a mainexample. It is however needless to say that a non-buried wiring(aluminum-based or refractory metal-based wiring) can also be used asthe multilayer wiring.

In the above embodiment, the high breakdown voltage MOSFET has beendescribed specifically with LDMOSFET as a main example. It is needlessto say that it can be applied similarly to a high breakdown voltageMOSFET of another type having a drain offset structure.

What is claimed is:
 1. A semiconductor device comprising: a substratehaving a main surface including a first region for a high breakdownMOSFET and a second region for a low breakdown MOSFET, the first regionhaving a first portion, a second portion and a third portionsequentially, the second region having a fourth portion and a fifthportion adjacently; a first shallow trench in the substrate at the firstportion; a first insulation film formed in the first shallow trench; asecond insulation film formed on the main surface of the substrate atthe third portion; a first gate electrode formed on the first insulationfilm and the second insulation film; a first semiconductor region and asecond semiconductor region formed in the main surface of the substrateat both sides of the first gate electrode; and a second shallow trenchin the substrate at the fourth portion; a third insulation film formedin the second shallow trench; a second gate electrode formed over themain surface of the substrate at the fifth portion, wherein the firstinsulating film extends on the main surface of the substrate at thesecond portion, herein the third insulating film is formed in the secondshallow trench at the fourth portion and does not extend on the mainsurface of the substrate in the fifth portion, and wherein the depth ofthe first shallow trench is equal to that of the second shallow trench.2. A semiconductor device according to claim 1, wherein the depth of thefirst insulating film at the second portion is greater than that of thethird insulating film at the fifth portion.
 3. A semiconductor deviceaccording to claim 1, wherein the first gate electrode is formed overthe first insulating film at the second portion contiguous to the firstshallow trench.
 4. A semiconductor device according to claim 1, whereinthe first insulating film and the third insulating film are siliconoxide films.
 5. A semiconductor device according to claim 1, herein thefirst gate electrode and the second gate electrode are poly-siliconelectrodes.